<%@page import="javax.imageio.ImageIO"%>
<%@page import="java.awt.Font"%>
<%@page import="java.awt.Graphics"%>
<%@page import="java.awt.image.BufferedImage"%>
<%@page import="java.util.Random"%>
<%@page import="java.awt.Color"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%!
private Color getRandColor(int fc, int bc)
{
    Random random = new Random();
    if (fc > 255)
        fc = 255;
    if (bc > 255)
        bc = 255;
    int r = fc + random.nextInt(bc - fc);
    int g = fc + random.nextInt(bc - fc);
    int b = fc + random.nextInt(bc - fc);
    return new Color(r, g, b);
}
%>
<%
String V_CODE = "vCode";

String STRING_CODE = "abcdefghijklmnopqrstuvwxyz1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ";
//设置返回格式
response.setContentType("image/jpeg");
// 清空缓存
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
// HttpSession session = request.getSession();
// 设置宽度
int width = 60, height = 20;
BufferedImage bi = new BufferedImage(width, height,
        BufferedImage.TYPE_INT_BGR);
Graphics g = bi.getGraphics();

Random random = new Random();
g.setColor(getRandColor(200, 250));
g.fillRect(0, 0, width, height);
g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
g.setColor(getRandColor(160, 200));
for (int i = 0; i < 155; i++)
{
    int x = random.nextInt(width);
    int y = random.nextInt(height);
    int xl = random.nextInt(12);
    int yl = random.nextInt(12);
    g.drawLine(x, y, x + xl, y + yl);
}

String sRand = "";
for (int i = 0; i < 4; i++)
{
    // String rand = String.valueOf(random.nextInt(10));
    int n = random.nextInt(STRING_CODE.length());
    String rand =STRING_CODE.substring(n, n + 1);

    sRand += rand;
    // sRand += rand;
    g.setColor(new Color(20 + random.nextInt(110), 20 + random
            .nextInt(110), 20 + random.nextInt(110)));
    g.drawString(rand, 13 * i + 6, 16);
}
session.setAttribute(V_CODE, sRand);
g.dispose();
ServletOutputStream responseOutputStream = response.getOutputStream();
ImageIO.write(bi, "JPEG", responseOutputStream);
responseOutputStream.flush();
responseOutputStream.close();
out.clear();
out = pageContext.pushBody();
%>